The technology described herein relates generally to gas turbine engine components and more specifically to devices for manually rotating the core of a gas turbine engine.
Gas turbine engines typically include a compressor, a combustor, and at least one turbine. The compressor may compress air, which may be mixed with fuel and channeled to the combustor. The mixture may then be ignited for generating hot combustion gases, and the combustion gases may be channeled to the turbine. The turbine may extract energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight, such as by driving a fan or propeller, or to power a load, such as an electrical generator.
The compressor and turbine are linked together via a shaft to form a rotating piece of turbomachinery located inside of a casing. This assembly may be referred to as a “core” of the gas turbine engine. During maintenance or repair operations it is often necessary to inspect blades and other elements of this rotating turbomachinery within the core. However, access to and visibility of this turbomachinery is frequently limited by the casing as well as other elements of the gas turbine engine.
Many gas turbine engines have one or more inspection ports, openings in the casing, which may be opened via removable plugs or covers to inspect and/or service (repair, replace, adjust, etc.) internal components. Inspection can be visual with the naked eye, or with mirrors or other optical tools such as borescopes. Frequently, however, these inspection ports are positioned such that only certain elements of the rotating turbomachinery are visible with the engine stopped and the turbomachinery in a fixed position. It is therefore often necessary to rotate the turbomachinery to view and/or service other components.
Rotation is typically accomplished by applying torque through a drive pad which is connected to an accessory gearbox. A socket is normally provided in the drive pad to receive a ratchet wrench or other hand tool, or an output shaft of a motorized drive unit. Manual operation of the drive pad, however, may prove difficult for an operator who needs to be proximate to an inspection port which may not be adjacent to the drive pad. Therefore, two or more persons may be required to rotate and inspect or service the turbomachinery. Motorized drive units may be operated remotely by an operator who is proximate the inspection port. However, motorized drive units are expensive, often cumbersome, and do not provide the operator with a “feel” for the rotation and momentum of the turbomachinery, making precise positioning and/or reversing of the rotation somewhat difficult and time consuming.
Accordingly, there remains a need for a device for manually rotating or turning a core of a gas turbine engine which is inexpensive yet portable and easy to use, and enables a single operator to rotate and inspect or service the turbomachinery.